This invention relates to solar energy systems; and more particularly, the invention relates to a solar heat exchanger for use in a solar energy system providing space heating and preheating of water for a commercial building or residence.
The price of hydrocarbon fuels has greatly increased during recent years and is likely to climb still higher. In addition, the reserves of such fuels have dwindled, forcing economists to look ahead to the day when the fuels might be unavailable at almost any price. Alternatives to hydrocarbon fuels, such as nuclear fusion power and coal, present concerns over safety and the environment, and have slowed the move toward such energy sources. Nuclear fusion plants, which promise virtually unlimited power, are still decades away from becoming a reality. Solar power, however, as an alternative, has many attractions. It produces neither pollution nor radioactivity, and it is virtually inexhaustible. Accordingly, in an increasingly resource-conscious society, solar energy is now being considered as an energy source for providing a major part of the heating required for houses.
In order to harness and put solar energy to work heating homes and offices, solar energy systems are required. The object of any type of solar heating system is to catch and accumulate enough of the dispersed energy of the sun to provide useful heat and store enough of it to last through nights and cloudy days.
Solar heating systems are classified as either passive or active. Passive systems collect solar heat and store it without hardware driven by mechanical energy. Active solar heating systems work more like conventional gas or oil heating arrangements, but the sun's radiation, instead of fossil fuels, provides much of the energy. These systems consist of collectors to absorb the sun's heat, ducts or pipes to transport it, and a heat storage area. The active components include fans, pumps, valves and thermostats.
Most solar energy collectors, which operate as heat exchangers, function in essentially the same manner. A metal surface (copper, aluminum or steel) is painted black to absorb solar radiation and is enclosed in a well-insulated glass or plastic-topped housing designed to trap the sun's energy and contain it to then be conducted into a portable medium for storage. The two media used to collect, transport and store heat are air and liquid (usually water).
In an air system, air circulating around the collector plates picks up heat and is moved into spaces to be heated. In a liquid system, a liquid passes through tubes attached to the collector surface, picks up heat by conduction, and then moves into a water storage tank for use as needed. Therefore, as can be appreciated, a critical element in any solar energy heating system is the solar collector or heat exchanger which must convert solar energy into stored heat, in the media used to transport and store the heat, in a highly efficient manner.
One solar heat converter in the prior art is that disclosed in U.S. Pat. No. 3,902,474 issued to the inventor of the present invention. The solar heat converter disclosed therein comprises a box having baffles therein that define an uncovered serpentine channel in the lower portion of the box. The channel leads from an air inlet port to an outlet port formed in the box. A thermal glass panel covers the box and exposes the interior of the channel to the sun's rays. The box also contains a piping system following a serpentine path through the box, which piping system contains a fluid that is heated within the box of the air going through the channel as well as by the radiant energy passing through the thermal glass panel.
Although the solar heat converter disclosed therein is an effective collector and converter of solar energy into heat for use in a building or residence, it would be desirable to increase the volume of air that can be effectively handled by a solar heat converter or heat exchanger of this type.